Software I: Utilities and Internals

Lecture 2 – The vi Text Editor

* Modified from Dr. Robert Siegfried original presentation

What is vi?

• vi is the most widely used full-screen text editor for UNIX and Linux system.

• vi is short for visual extension (of the line-oriented editor ex) developed by Bill Joy, co-founder of Sun Microsystems.

• The UNIX/Linux editor succession is ed → ex → vi

• The main alternate editor, EMACS, was developed at MIT.

User Profile• When a user logs in, there is a profile that is used to initialize the terminal

session:[SIEGFRIE@panther ~]$ more .bash_profile# .bash_profile

# Get the aliases and functionsif [ -f ~/.bashrc ]; then . ~/.bashrcfi

# User specific environment and startup programs

PATH=$PATH:$HOME/bin

export PATHunset USERNAME[SIEGFRIE@panther ~]$

Starting vi

• To invoke the vi editor, typevi <filename>

• If the file is new, you will get a nearly-blank screen.

• You are initially in command mode. By typing, i or a, you can start to enter text.

Opening vi Screen~~~~~~~~~~~~~~newfile [New File] 0,0-1 All

Command and Input Mode

CommandMode

InputMode

<ESC>

a, A, i, I, o, O

Entertext

Edittext

Nota bene: You always start in command mode

ex Commands in vi

• ex commands are always available for use in vi command mode if you first type ":"

• Examples:s/x/y/ will substitute an y for x.

:., +1j will join the current line with the following line.

• Finish the command by pressing just as you would in ex.

Entering Input Mode

a Append after current cursor position.

A Append after current line.

i Insert before current cursor position.

I Insert before current line.

o Open line below current line.

O Open line above current.

Working in Command Mode

• The command never appears on the screen (except for ex commands).This is newtext enter using "d"~~~~~~~~:s/"a"/"d"/ 2,1 All

Leaving Input Mode

• To get back to Command Mode, press the "Escape" key.

• When in doubt about which mode you are in , press "Escape."

• If you press "Escape" in Command Mode, vi will beep.

Exiting Input Mode

Hello, worldMy name is Sy.~~

~~~~~~~~~~~~ 2,14 All

Enter "a" in Command Mode

Press ESC in Input Mode

Exiting vi

• To write and/or quit your vi session:

:w Writes the files:wq Writes and quits:x Same as :wqZZ Same as :wq:q Quits without writing (if unmodified):q! Quits without writing

vi tells you the Number of Lines

#include <stdio.h>

int main(void){ printf("Hello, world\n"); return(0);}~~~~~~~~~~"hello.c" 7L, 78C 6,2-9 All

Moving Around the Screen

h j k l

0 Beginning of current line$ End of current line Beginning of next line+ Beginning of next line- Beginning of previous line

Hello there Today isThursday. Itis raining and it ishumid.~~~~~~~~~~ 4,6 All

$

<sp><sp>

jj

Other Move Commandsw move to the next word or punctuation

e move to the end of the next word of punctuation

b move to the beginning of the previous word

) move to the beginning of the next sentence

( move to the beginning of the current sentence

} move to the beginning of the next paragraph

{ move to the beginning of the current paragraph

vi Words and Paragraphs

• vi sentences end with ".", "?" or "!"• vi paragraphs begin after a blank line.

Hello world again.This is a mysterious file.

Help~~

w}b

}w

Moving Around Faster

^f Writes the files

^d Move forward ½ screen

^b Move backward one full screen

^u Move backward ½ screen

G Moving to the end of the file

A number in front changes the command3^f – move ahead 3 screens99G -go to line 99

Modifying Text

• r char – replace the current character with char.

• R string <esc> - Overwrite text with this string.

• J – joins current and next line into one line.• ~ - Switches upper and lower case.

Deleting Text

x deletes a single character

num x delete num characters

dw deletes the rest of the current word

num dw deletes num words from the current position

d$ deletes the rest of the line

d) deletes to the beginning of the next sentence

dd deletes current line

dnumd deletes num lines from the current line

Moving Text

• Lines last deleted are placed in a buffer. You can "put" it anywhere in a file.

p – put it to the right or below the current position.

P – put it to the left or above the current position.

Moving Text – An Example

Line 1

Line 2

Line 3

Line 4

Line 3

Line 4

Line 1

Line 2

Afterd2djp

Searching For Text

• /string – search forward for string• ?string – search backward for string

Copying and Moving Text

• To copy text, use yy (to yank a line) or yw (to yank a word) or y$ (to yank until the end of the line) or y) (to yank until the next sentence) followed by p or P.

• To move text, use dd,dw, d$ or d) followed by p or P.

Using ex Commands in vi

• All ex commands in vi are preceded by a colon:

:wq

:q!

Some Useful ex Commands

:address s/oldpattern/newpattern/ - replace the old pattern in the text with the new pattern on these lines

:address d – deletes these lines

:g/opattern/s//npattern – globally searches for opattern and replaces it with npattern. (once per line)

:g/opattern/s//npattern/g – globally searches for opattern and replaces it with npattern. (all occurences)

:r file – reads in file

:! cmd – perform UNIX shell command cmd.

Addresses in ex Commands

• Address in these commands can be:

1, 5 – lines 1 through 5

., 30 – current line through line 30

30, $ - line 30 through the end

., +5 – current line through 5 lines downs

:-3, +1 – 3 lines above until 1 line down

Miscellany and Metacharacters

• ^l – refreshes screen• Metacharacters

^ - beginning of line

$ - end of line

. – matches any single character

* - matches preceding character any number of times

[string] – matches any character in string

[^string] – matches any character NOT in string.

Metacharacters – An Example

• /^xyz – search for xyz at beginning• /line.$ - search for this at the end of the line• /^$ - search for empty line• s/X.*$/Hello – finds X followed by any character

any number of times at end of line and replaces it with Hello.

• :1, $s/[0-9]/-/g• :1,$s/[^a-za-Z]/0/g• :s/United .*ica/USA/• http://vimregex.com/#address